Implantable hemodialysis access device

ABSTRACT

A hemodialysis port comprising a flexible housing member defining one or more ports. Each port has a selectively-permeable septum member disposed thereon to permit medical devices, for example, Huber needles, sheath and/or dilators to be inserted therein. At the interface between the housing and the septum, a spring member is provided to provide an axial force on the septum which seals the puncture created by the aforementioned medical devices. In one exemplary embodiment, the hemodialysis access port of the present invention is comprised of a plurality of ports designed for multiple hemodialysis treatments over the life of the port. In other exemplary embodiments, the bottom of each port may comprise a needle stop insert formed of, for example, metal, titanium, stainless steel or ceramic.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional patentapplication Ser. No. 60/199,714, filed Apr. 26, 2000, the entiredisclosure of which is incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to an implantable biocompatible accessdevice used in conjunction with hemodialysis and the delivery ofmedicants and other fluids into a body, or the withdrawal of fluids fromthe body.

BACKGROUND OF THE INVENTION

Access to a patient's vascular system can be established by a variety oftemporary and permanently implanted devices. Most simply, temporaryaccess can be provided by the direct percutaneous introduction of aneedle through the patient's skin and into a blood vessel. While such adirect approach is relatively simple and suitable for applications suchas intravenous feeding, intravenous drug delivery, and otherapplications which are limited in time, they are not suitable forhemodialysis and other extracorporeal procedures that must be repeatedperiodically, often for the lifetime of the patient.

For hemodialysis and other extracorporeal treatment regimens, a varietyof transcutaneous catheters and implantable ports have been proposedover the years. Prior medical transcutaneous catheters comprise a singlecatheter tube having a distal end placed in a vein in an inu-dwellingmanner and a proximal end which extends through the skin and which isavailable for connection to a hemodialysis or other blood treatmentsystem.

Implantable infusion devices or ports, in contrast, are entirelysubcutaneous and connected to a vein to an artery by a subcutaneouscannula. Access to the port is achieved by percutaneous placement of aneedle or other connecting tube. Such ports typically comprise aneedle-penetrable septum to permit percutaneous penetration of theneedle. However, conventional ports do not allow the needle to penetratedeeply into the port. Because of this, a small displacement of theneedle can cause it to be pulled from the port. In cases where locallytoxic materials are being infused, extravasation of such materials cancause local tissue damage which may require corrective surgery such asskin grafting or removal of tissue. Recently, several valved-portdesigns have been proposed, where introduction of a needle or otheraccess tube opens a valve to provide flow to the cannula which connectsto the blood vessel.

Both the transcutaneous and subcutaneous implanted port vascular accesssystems described above suffer from certain disadvantages andlimitations. For example, both such systems permit only limited bloodflow rates. In the case of transcutaneous catheters, the limited flowrates result from the generally small lumen diameters available inin-dwelling catheters. In the case of implanted port access systems, thelimited flow rates have resulted from both the port structure and therelatively small lumen diameters available in the cannulas which connectthe port to the blood vessel. Such limited blood flow rates areproblematic since they prolong the duration of the associatedextracorporeal blood treatment protocol, such as hemodialysis,hemofiltration, and apheresis.

The subcutaneous placement of the catheter or cannula which is connectedto or implanted within the blood vessel and brought to the externalattachment point, i.e., either the implanted port or transcutaneoustract through the skin, is difficult in a number of respects. For,example, catheters and cannulas having their distal ends implanted inthe jugular vein are typically bent by an from 90° to 180° to locatetheir associated ports or catheter exit points at an appropriatelocation on the patient's chest. Such bends also can accommodate excesslength in connecting catheters and cannulas. The bends, however, arealso subject to kinking and other problems.

One attempt at solving other problems is found in U.S. Pat. No.5,387,192 to Glantz, et al. This patent disclosed a subcutaneouslyimplantable access port, includes a two piece plastic jacket, comprisedof a cowl and a base, which surrounds a metallic reservoir. The metallicreservoir has an open top and a closed bottom. The open top of thereservoir is sealed by the septum to define a chamber. The non-metalliccowl includes a septum opening and a flange positioned adjacent to thetop of the opening. The non-metallic base includes a reservoir openingin which the metallic reservoir is received. The cowl and base arepositioned to define a forming zone and are connected at the formingzone to substantially surround the metal reservoir.

One problem encountered such devices having fluid cavities and separateexit passageways through which the fluids will travel, is the formationin such devices of seams, having corners and edges. As blood or otherfluids are injected into a fluid cavity, pressure develops within thecavity causing the fluid to flow through the exit passageway. As aresult of the fluid flowing past these seams, edges and corners,turbulence may develop, which will affect some fluids, such as blood,which are sensitive to turbulence. A further problem with the reservoircup is that dead spots are created in the areas where the floor of thecup meets the exit passageway retarding the fluid flow, leading tostagnation or the formation of clots or blockages in the port.

A series of U.S. Patents to William Ensminger, et al., discloses accessports having internal lumens for receiving a percutaneously introducedaccess device (e.g. a needle or catheter/stylet combination) andinternal valve structures for isolating the port from an associatedimplanted catheter. These patents, disclose a number of specific valvetypes which may be incorporated within the access port, includingleaflet valves, ball valves, flapper valves, and other specificconfigurations which are referred to as “articulating valves.” All suchstructures, however, generally require that the access device be passedthrough the valve itself (i.e., the portion which closes the blood flowpath through the valve) in order to cause the valve to open. Such arequirement presents the risk that the valve will be degraded by directcontact with the access device after repeated uses so that portions ofthe valve may be degraded and released into circulation. Such valvesalso present a significant risk of failure after repeated use or contactwith a sharpened needle. Additionally, such valve structures can damagethe access device as it is being introduced therethrough, thuspotentially disrupting valve flow through the needle during a subsequenttreatment protocol.

In U.S. Pat. No. 5,704,915 to Melsky, et al., a dual access port forhemodialysis comprising a pair of conical or funnel-like shells isjoined tangentially at their outer surfaces. Each shell having arelatively large entrance and a relatively small exit end. Aself-sealing septum closes the entrance of each shell and a pair ofoutlet tubes extend from the exit ends of each shell. The conicalconfiguration places the septum of each shell opposite the outlet tubeso that when a needle accesses the port, it will lie in line with theoutlet tube. A bend in the shell prevents the access needles from beingadvanced to a point where the needles can puncture the walls of theattached catheter. The shells include a carbon insert or liner to createa thromboresistant as well as scratch resistant surface over most of theshell's interior. In the areas which are likely to be contacted by thetip of the needle, pyrolitic carbon coating may be used. The remaininginterior surface, for example at the outlet tube, can be titanium.

A problem with the Ensminger and Melsky devices is that the entry portsare usually inclined at a substantial angle relative to the skin surfacethrough which the access device is introduced. Such angled accessrequires that the personnel introducing the access device guess theangle and estimate the optimum insertion point on the patient's skin.Such uncertainty in the device penetration is perhaps why these designsall require the use of enlarged “funnel” for receiving and aligning theneedle as it is introduced. It would thus be advantageous to provideaccess ports having entry passages which are disposed generally“vertically” (i.e., at an angle which is substantially normal to theskin surface through which the needle is being introduced). Bypenetrating the needle “straight in,” it is much easier to align theneedle with the target orifice and the size of the orifice area can bereduced.

Accordingly, there has been a need for an improved an implantable,subcutaneous single or multi-port vascular access device forhemodialysis and other drug delivery applications, which overcomes theabove-noted problems.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides an improved hemodialysisaccess port having a flexible non-metallic housing. In one exemplaryembodiment, multiple ports are provided. The multiple ports allow forextended life of the device and less trauma to the tissues. In anotherembodiment, a single port is provided. Each port includes a circularopening sealed by a self-sealing septum, rubber or silicone, forexample, a generally conical or funnel shaped chamber for receivingfluid extends from the circular opening at an angle. The circularopening will be generally parallel to the skin's surface allowingvertical penetration. The funnel section includes an insert formed of,for example, metal, titanium, stainless steel, or ceramic. The insert ismolded, pressed or bonded at the base end of the funnel section, leadingto an integrated outlet, to serve as a needle stop to prevent potentialpenetration of needles through the plastic housing. This configurationalso permits access by a blunt flexible catheter through the funnel tothe outlet.

In specific exemplary embodiments, the present invention provides ahemodialysis port comprising a housing defining a plurality ofinterconnected chambers, each said chamber having a bottom portion andsidewall portions; a septum attached to said side wall portions of eachsaid chamber enclosing said chamber; and a spring mechanism disposedbetween said sidewalls and said septum and applying an inward force onsaid septum.

The present invention also provides a method for performinghemodialysis, comprising the steps of inserting at least one multi-portdevice under the skin of a patient; inserting a needle and sheaththrough said skin and into one of said ports of said multi-port device;removing said needle from within said sheath, leaving said sheath insaid port; and inserting a cannula and obturator into said sheath anddrawing from said cannula blood from within said port.

The present invention also provides a separate hemodialysis methodcomprising the steps of inserting a multi-port device under the skin ofa patient; inserting a hollow needle into one of the ports of saidmulti-port device through the skin of said patient; inserting aguidewire through said needle and into said port; removing said needlefrom said port and said patient; and inserting an introducer over saidguidewire and into said port.

The individual ports may be connected to a single outlet tube orpassage. Alternatively, each port may lead to separate outlet tubes, forexample when it is desired that one port be used for infusion whileanother port be used for withdrawal. Each port has an open center andflanges retains the septum which fits over the top edge of the circularopening of a port and is further retained in the opening by means of acircular wound or “clock” spring configured around its periphery toapply continuous hoop pressure over the life of the port. Each of thesepta include identification features incorporated on their uppersurfaces to distinguish one from the other.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of the exemplary multiple access portaccording to the present invention;

FIG. 2 is another cross-sectional view of the exemplary multiple accessport according to the present invention;

FIG. 3 is a front view of an access port according to the presentinvention;

FIG. 4 is a perspective view of the exemplary multiple access portaccording to the present invention;

FIG. 5 is a cut-away perspective view of the exemplary multiple accessport according to the present invention;

FIG. 6 is a perspective view of a septum according to the presentinvention;

FIG. 7 is a top plan view of a septum according to the presentinvention;

FIG. 8 is a cross-sectional view of a septum according to the presentinvention;

FIGS. 9-11 depict one exemplary method of use of the hemodialysis of thepresent invention; and

FIGS. 12-16 depict another exemplary method of use for the hemodialysisport of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENT

FIGS. 1-5, depict various views of the exemplary low-profile multipleport implantable access device 10 of the present invention. The accessdevice 10 generally comprises a housing member 25 including circularopenings 5 a, 5 b and 5 c on the upper side of the housing and base 11on the bottom on the housing. The housing 25 is constructed from abiocompatible non-metallic material, such as plastic, and is moderatelyflexible as to allow for improved anatomical placement over curved orirregular sections of the fascia musculature. Flexibility, in thissense, is not easily definable since many factors, such as patientanatomical profile data, patient comfort, doctor preference, etc., willgo in to determining how flexible the housing should be. Thus, thepresent invention recognizes that the flexibility spectrum is ratherlarge, and may be determined on a patient-by-patient basis, or maycomprise flexibility standards based, on, for example, patient profiledata, average patient profile data, etc., and the present invention isintended to cover all such alternatives. The housing 25 and ports 3 a, 3b and 3 c have circular openings 5 a, 5 b and 5 c, defining fluidchambers 15 a, 15 b and 15 c. The chambers are sealed by the housing 25,and self-sealing septum members 20 a, 20 b and 20 c, arranged in thecircular openings. Preferably the septum is constructed of silicone orsimilar elastomeric material, or rubber. For hemodialysis applications,the septum can have a durometer ranging from 30-55, since it isunderstood that the septum must withstand several large-diameterinsertions while still maintaining fully sealed integrity.

The circular openings 5 a, 5 b and 5 c in ports 3 a, 3 b and 3 c aregenerally parallel to the skin's surface allowing for substantiallyvertical penetration of a needle 35 or catheter 30. The fluid chambers15 a, 15 b and 15 c are generally conical or funnel-shaped and extend atan angle in relation to the circular openings. Such configurationassists in providing better flow characteristics, easy access to eachport and enables a low-profile shape.

The funnel sections 18 a, 18 b and 18 c taper (narrow) in diameter asthey approach integrated outlet passageways 19 a, 19 b and 19 crespectively. In the exemplary embodiment, integrated outlet passageways19 a, 19 b and 19 c connect to single outlet tube 2, which deliversfluid out of the chambers 15 a, 15 b, and 15 c and integratedpassageways 19 a, 19 b and 19 c to a predetermined location, via stemand attached catheter (not shown), as is understood in the art.

Such connection may be made consecutively with one passageway flowinginto another or may be arranged with separate passageways conjoining ator near the outlet tube 2. In another embodiment, the passageways mayremain separate, connecting with separate outlet tubes, for example,where one port and passageway is used for infusion or to deliver fluidand another port and passageway for withdrawal.

The funnel sections 18 a, 18 b and 18 c, particularly the bottomportions 16 a, 16 b and 16 c thereof, include a metallic, titanium,stainless steel, for example, or ceramic insert. The insert at thebottom portions, 16 a, 16 b and 16 c are molded, pressed, welded, bondedor attached by other known means, toward the base end of the funnelsections 18 a, 18 b and 18 c, leading to integrated outlet passageways19 a, 19 b and 19 c, and are of sufficient length and width to serve asa needle stop to prevent potential penetration of needles 35 throughport 3 a of the access device 10, as shown in FIG. 1. This configurationalso permits access by a blunt flexible catheter 30 in port 3 a throughthe funnel 19 a to the integrated outlet passageway 18 a, shown in FIG.2.

Referring to FIGS. 3-5, can be seen base 11 of housing 25 and integratedsuture holes 12 to further secure the implantable access device 10 tothe patient. Similar to the housing 25, base 11 is moderately flexibleas to allow for improved anatomical placement and securement of theaccess device 10 over the fascia musculature.

Flow valves (not shown) may be provided on each chamber to prevent backfluid from entering the chamber, i.e., the flow valves may be formed topermit only one direction of fluid travel.

Turning to FIG. 5, is seen ports 3 a, 3 b and 3 c, each port having anopen center and flanges 13 a, 13 b and 13 c located around the peripheryof the top edge of circular openings 5 a, 5 b and 5 c which engagegrooves 23 of septa 20 a, 20 b and 20 c and flanges are dimensioned soas to force against the septum, thereby holding the septum in place.Circular wound or clock springs 21 a, 21 b and 21 c are arranged in theupper portion of chambers 15 a, 15 b and 15 c, respectively, positionedaround the periphery and below the circular openings 5 a, 5 b and 5 c ofeach port. Such springs are configured so as to apply continuous hooppressure over the life of the access device and in conjunction with theflanges, further retain the septum in the port opening. The springs 21a, 21 b and 21 c are preferably formed of titanium, stainless steel,ceramic, and/or other biocompatible material.

As best seen in FIGS. 6 and 8, septum 20 is preferably formed of siliconor other semi-permeable materials that permit ingress and egress ofneedles to deliver fluid to the chambers. In the exemplary embodiment,septums 20, and 20 a, 20 b and 20 c as shown in the drawings, are formedwith a generally circular shape, and, may include a nipple or otheridentification feature incorporated on the upper generally concavesurfaces 21 thereof to distinguish one from the other. A nipple orsimilar raised feature may be advantageous for visual and/or tactilelocation and identification of each port of the access device 10, but isnot necessary for the present invention. In an alternative embodiment,concave surfaces 21 may have an indented or recessed identificationfeature, where a protruding feature is undesirable. The septums 20, and20 a, 20 b and 20 c are preferably formed with tongue and grooveportions 23, which mate with flanges 13 am 13 b and 13 c located at thetop edges of the circular openings 5 a, 5 b and 5 c of the ports 34 a, 3b and 3 c. The lower portion 24 of the septums 20, 20 a, 20 b and 20 care sized so as to be held securely against the inner surfaces of clocksprings 21 a, 21 b and 21 c.

Referring now to FIGS. 9-11, a first exemplary method of use of thehemodialysis port of the present invention is depicted. In FIG. 9, andassuming that the port 10 has been properly inserted into a patient, asis understood by one skilled in the art, a needle 50 and sheath 52 areinserted into one of the chambers, e.g., 8C, through the skin. In FIG.10, the needle 50 is removed leaving only the sheath 52 remaining in thechamber of the device 10. In FIG. 11, a cannula or obturator 54 isinserted into the sheath. The obturator may comprise a hub section 56and may further include an ingress/egress port 58 to draw bodily fluidsfrom within the chamber 8C or to insert medicament into said chamber.Generally, in the hemodialysis art, port 58 will be utilized to drawblood through the device so that the blood may be taken to ahemodialysis machine for processing. The blood can likewise be returnedto the device and eventually to the body via port 58. The obturatorprovides consistent blood flow during the hemodialysis process. Afterthe hemodialysis process, the obturator and sheath may be removed (notshown) and the process repeated as required for hemodialysis. Oneadvantage of the process of FIGS. 9-11 is the use of technology that iswell known to those in the diagnostics/interventional cardiology art,i.e., the use of a needle, sheath, and cannula/obturator device.

FIGS. 12-16 depict a second exemplary method of use of the hemodialysisport of the present invention. As with the previous exemplary method ofuse of FIGS. 9-11, the port 10 is implanted into a region, for example,just below the breast. In typical applications, two ports are implantedon either side of the body. For hemodialysis applications, the ports areconnected to the aorta for inflow and outflow to the dialysis equipment.In FIG. 12, a needle 60 (e.g., Huber needle) is inserted through theseptum of the port assembly, as shown. In FIG. 13 a guidewire 62 isinserted through the needle 60 into the port assembly. In FIG. 14, theneedle 60 is removed, leaving only the guidewire in the port assembly asa reference point. FIG. 15 depicts insertion of an introducer 64 overthe guidewire, through the skin and into the septum. As is understood bythose skilled in the art, the introducing cannula 64 is sufficient rigidaxially to be inserted through the skin and into the port through theseptum. The introducer may comprise a hub 66 for application of adilator. FIG. 16 depicts the hub 66 to remove exposing an opening 70 forinsertion of a dilator. FIG. 16 also depicts an ingress/egress port 68,which operates similar to port 58 shown in FIG. 11. Once the dialysisprocess is over the introducing cannula 64 and guidewire 62 may beremoved.

Thus, it is apparent that there has been provided an implantablemultiple port vascular access device that satisfies the objectives setforth herein. Those skilled in the art will recognize that the presentinvention is subject to modification and/or alterations, all of whichare deemed within the scope of the present invention, as defined in theappending claims.

1. A hemodialysis port comprising: a housing defining a plurality ofinterconnected chambers, each said chamber having a bottom portion andsidewall portions and integrated passageway providing interconnection ofsaid chambers; each said chamber further comprising a funnel portiontapering from said sidewall portions and said bottom portions a septumattached to said side wall portions of each said chamber enclosing saidchamber; and a spring mechanism disposed between said sidewalls and saidseptum and applying an inward force on said septum.
 2. A port as claimedin claim 1, wherein said spring mechanism having sufficient force toclose an opening in said septum caused by a needle or other medicalinstrument.
 3. A port as claimed in claim 1, said bottom portion furthercomprising a titanium insert covering at least a portion of said bottomportion of said port.
 4. A port as claimed in claim 1, wherein saidhousing comprising a flexible material having a flexibility for aparticular patient's anatomical structure.
 5. A port as claimed in claim1, wherein said septum comprising silicon rubber.
 6. A port as claimedin claim 1, wherein said chambers are connected together to a manifoldto provide a single inlet/outlet to and from said chambers.